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(11) | EP 0 600 436 A3 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | Semiconductor device, circuit and method of manufacture |
| (57) A monolithic integrated circuit capable of operation in the microwave range which
is fabricated using silicon technology wherein transmission line interconnects are
fabricated along with active devices on the same substrate. The transmission line
is provided using polycrystalline silicon since it can have much higher resistivity
than single crystal silicon. Accordingly, a circuit is provided wherein active devices
are provided in single crystal silicon and interconnects are formed overlying polycrystalline
silicon to provide transmission line interconnects between devices and obtain the
desired high frequency response. This is accomplished by providing a highly doped silicon substrate of predetermined conductivity type having a less highly doped silicon layer thereon of the same conductivity type with an oxide layer over the less highly doped layer, forming mesas for formation therein of active elements in the structure having valleys between the mesas extending into the substrate, filling the valleys with very high resistivity polysilicon, forming an electrically insulating layer over the polysilicon, forming active elements with contacts thereto in the mesas and forming interconnects between contacts of the active elements extending over the high resistivity polysilicon regions and the electrically insulating material thereover. |